If you don't mind doing a little soldering, you can buy these 1800mAh NiMH AA for ~$1.25 each:
http://www.amondotech.com/index.asp?...ROD&ProdID=206
8C TX pack would cost exactly $10. I've check them with my Triton cycler and they do indeed put out a little over 1850mAh at the typical TX current draw.
I am sure there are other sources out there, but this one is where I've been buying mine lately.